Visual tests: violin

basic

scale area to sample size (C is smaller)

narrower (width=.5)

with tails and points

with smaller bandwidth and points

dodging

coord_polar

coord_flip

dodging and coord_flip

continuous x axis, multiple groups (center should be at 2.0)

continuous x axis, single group (center should be at 1.0)

grouping on x and fill

grouping on x and fill, dodge width = 0.5